1. Field of the Invention
This invention relates to antennas which are usable on a motor vehicle for mobile communication and, more particularly to mounting assemblies for such mobile antennas.
2. Description of the Prior Art
As a mobile antenna of the type concerned, a sleeve type antenna has heretofore been widely used particularly for high-frequency communications, as in an automotive telephone system. Such a sleeve type antenna is ordinarily mounted on a rear fender of the motor vehicle or in the vicinity thereof since, in that position, it is not electromagnetically influenced by the roof, or other body portion of the vehicle, to any substantial extent. An antenna mounted in this manner, however, involves the danger that the antenna element be broken, as when the vehicle is washed by an automatic car washer or is put into a garage. To cope with this situation, the antenna is constructed conjointly with a coaxial cable so as to be readily removed when desired. One example of such an antenna mounting assembly is disclosed in U.S. Pat. No. 4,173,761. Such a mounting assembly, however, involves the danger of the antenna element being stolen. If the mount is designed so that the antenna can be removed and remounted only by use of a particular tool means, there would be a substantial inconvenience in use of such an antenna unit.
One known form of antenna designed to prevent damage and theft thereof is a so-called rod antenna for car radio use. This rod antenna is slidingly telescoped to a closed position within the fender or other body panel of the vehicle to which the antenna is mounted. In this case, however, the antenna element must be formed of a rigid metal material as the electrical connection between the antenna element and the coaxial cable is effected by contactor means. Therefore, there is the danger of the antenna element being broken when struck against an obstacle or other object during travel of the vehicle. It is known to provide a spring at the mounting base of the antenna element as a means for preventing a breakage thereof. This mounting means, however, makes it difficult for the element to be removed from or stored inside the body panel of the vehicle, thus involving the danger that the element or the body panel might be damaged for example, in a car washing operation.